apache/iceberg · error · UnsupportedOperationException

Variant is not supported

Error message

Variant is not supported

What it means

OrcSchemaWithTypeVisitor's variant() callback handles ORC variant nodes paired with an Iceberg Types.VariantType; the base-class default throws UnsupportedOperationException. Any concrete visitor that does not override it will throw when the schema walk reaches a variant type.

Source

Thrown at orc/src/main/java/org/apache/iceberg/orc/OrcSchemaWithTypeVisitor.java:114

    return visitor.variant(iVariant, variant, metadataResult, valueResult);
  }

  public T record(
      Types.StructType iStruct, TypeDescription record, List<String> names, List<T> fields) {
    return null;
  }

  public T list(Types.ListType iList, TypeDescription array, T element) {
    return null;
  }

  public T map(Types.MapType iMap, TypeDescription map, T key, T value) {
    return null;
  }

  public T variant(Types.VariantType iVariant, TypeDescription variant, T metadata, T value) {
    throw new UnsupportedOperationException("Variant is not supported");
  }

  public T primitive(Type.PrimitiveType iPrimitive, TypeDescription primitive) {
    return null;
  }
}

View on GitHub (pinned to 86d9c8fc54)

Solutions

1. Upgrade iceberg-orc to a release with variant support so built-in visitors override variant().
2. Override variant() in your custom OrcSchemaWithTypeVisitor to return a handled value.
3. Use Parquet/Avro for tables containing variant columns.
4. Drop variant columns from ORC-backed tables before running schema operations.

Example fix

// after: override in visitor subclass
@Override
public T variant(Types.VariantType iVariant, TypeDescription variant, T metadata, T value) {
  return value; // propagate handled child result
}

// detect variant columns in the ORC schema before visiting
boolean hasVariant = streamChildren(schema).anyMatch(t -> t.getCategory() == TypeDescription.Category.STRUCT && isVariantStruct(t));

try { OrcSchemaWithTypeVisitor.visit(iType, schema, visitor); } catch (UnsupportedOperationException e) { if (e.getMessage().contains("Variant is not supported")) { degradeGracefully(); } else throw e; }

When it happens

Trigger: OrcSchemaWithTypeVisitor.visit dispatches to visitVariant → visitor.variant() on a schema containing an ORC variant, and the visitor subclass has not overridden variant().

Common situations: Schema conversion or read/write planning over Iceberg tables with VariantType stored as ORC; custom visitors built on older Iceberg versions that predate variant support.

Related errors

• Variant is not supported
• Unsupported type: variant
• Unsupported type: variant
• Unsupported type: variant
• Cannot handle

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/1850688dd3f086a0. Report an issue: GitHub.